The peer-reviewed literature describes PDRN as a mixture of deoxyribonucleotides with molecular weights between roughly 50 and 1,500 kDa, obtained by controlled purification and sterilisation of sperm DNA from Oncorhynchus mykiss (salmon trout) or Oncorhynchus keta (chum salmon). It was originally isolated from human placenta in Italy. The literature attributes its activity mainly to engagement of adenosine A2A receptors plus supply of nucleosides and nucleotides to the salvage pathway, and reports wound healing, anti-inflammatory, angiogenic, osteoblast and collagen synthesis effects across pre-clinical and clinical studies. The strongest clinical data sit with injected polynucleotide and PDRN products, including a randomised split-face trial of 27 participants comparing an injectable against a hyaluronic acid filler.

On the sourcing and purity numbers, the cosmeceuticals review describes PDRN as a registered proprietary drug recovered at greater than 95 percent purity of active substance. That ">95%" figure in the peer-reviewed literature refers to the purity of the preparation, not to similarity with human DNA.

I found no primary genomics source stating that salmon or trout DNA is 95, 96 or 98 percent similar to human DNA. The two nearest real figures are different things. The Atlantic salmon genome paper uses ">95% sequence similarity" to describe salmon's own internally duplicated chromosome regions compared against each other, not salmon compared against human. The zebrafish reference genome paper reports that roughly 70 percent of human protein-coding genes have at least one clear zebrafish orthologue, which is a count of shared genes rather than a percentage of sequence identity, and it is the standard fish to human benchmark.

On topical delivery, a 2025 in vitro paper states directly that PDRN's topical use is limited by its high molecular weight and anionic charge, which restrict skin penetration, and that plasma treatment was needed to reduce its size and neutralise its charge before cell uptake improved. Specialist clinical press makes the same point: PDRN-sized molecules sit far above the roughly 500 Dalton threshold generally applied to passive stratum corneum penetration, the targets are dermal fibroblasts, and absent disclosed molecular weight, encapsulation method and in vivo delivery data, topical claims remain unsubstantiated. That source also notes a late-2025 topical study using a low molecular weight peony-derived PDRN, which it describes as a single small study on a material not representative of most products on the market.